In order to carry out or repeat the grinding of cylindrical objects, such as for example cylinders for rolling mills and the like, in particular in an automatic cycle without operators, it is necessary to trace the geometry and the surface condition of the piece during working itself in order to influence the cycle in progress as a function of the measurements and to guarantee the maximum precision demanded for such work.
Such operations are carried out by means of transducers operating both in contact with the surface and at a distance from it which, in a conventional case of the grinding machine, are mounted on the moveable carriage supporting the grinding tool, and sweep along the workpiece surface following the movement of the tool.
This means that the speed of scanning the workpiece and the speed of machining it must be the same; however, some types of tracing require scanning times substantially longer than the times required for the tool to perform a grinding pass and therefrom it is necessary either to reduce the speed operating to adapt it to that required by the tracing devices, with a consequent prolongment of grinding times, or to carry out only a partial tracing of the piece with incomplete scanning of its surface during each pass by the tool, arriving at the complete scan by statistical means after a number of passes.
Furthermore, the positioning of measuring instruments in the vicinity of the tool may lead to a reduction in the life of such devices, owing to the presence of swarf and of vapors caused by the grinding process; in addition, it is possible for vibrations to occur in the carriage carrying the tool as a result of the working, and such vibrations may be transferred to the measuring instruments, reducing the precision of the measurements registered by them.